The present disclosure relates to an image reading device, an image forming apparatus, and an image processing method capable of executing shading correction processing for read image data.
In an image reading device such as a scanner, an image reading portion having a light source and a photoelectric conversion element may be placed being fixed with respect to a reading position for image data. An image reading device of this type performs shading correction for correcting variation in light emission characteristics of a light source or in light reception sensitivities of photoelectric conversion elements based on reference data read from a reference member placed being opposed to the image reading portion.
If a foreign material such as dust adheres to the reference member, in reference data read from the reference material, the density of a pixel corresponding to the adhesion position of the foreign material increases. Therefore, a white vertical line may occur in image data obtained through execution of shading correction, whereby the image quality of read image data may be reduced. In this regard, there is known an image reading device capable of eliminating an influence of a foreign material adhering to a reference member by superimposing a high-frequency component contained in initial reference data read from the reference member at a stage of shipment of the image reading device, onto a low-frequency component contained in reference data read from the reference member before reading of a document.